Polyhalogenated diarylalkanes, e.g. decabromodiphenylethane, are known flame retardants for use in polyolefin and polystyrenic-based formulations. On a commercial basis, the polyhalogenated diarylalkane is supplied to the formulation as a product predominant in the polyhalogenated diarylalkane selected. Heretofore, known formulations of polyhalogenated diarylalkanes were brominated at the aryl rings(s) exclusively. Thus, such formulations were thus less desirable when the circumstance of use of the flame retardant called for the beneficial aspects of an aliphatically brominated composition.